Solving a harbor accretion problem: the case of Miller and, Îles-de-la-Madeleine, Quebec

Abstract

This paper summarizes a group of studies regarding Millerand harbor, located on the Îles-de-la-Madeleine coast, which blocks most of the local littoral drift. The understanding and quantification of this sedimentological problem was first carried out using numerical models. Various schemes were then tested in two mobile-bed physical models. Finally, the impact of these solutions on the wave climate in the harbor and in the entrance channel was compared using a diffraction–reflection numerical model. The results show that accretion in Millerand harbor will only be controlled by the construction of a breakwater. This breakwater must close the east side of the harbor and must reach at least 2 m depth at its toe. It is also strongly recommended that two groins be built on the east-side beach to control the erosion of the cliff. The results of the diffraction–reflection model finally give some latitude to the harbor planners, as several schemes present satisfactory wave agitation maps. Key words: erosion, accretion, breakwater, diffraction–reflection, harbor, littoral drift, numerical model, physical model, wave hindcasting.